WO1993009616A1 - Coding method for broadcast transmissions - Google Patents

Coding method for broadcast transmissions Download PDF

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Publication number
WO1993009616A1
WO1993009616A1 PCT/GB1992/001997 GB9201997W WO9309616A1 WO 1993009616 A1 WO1993009616 A1 WO 1993009616A1 GB 9201997 W GB9201997 W GB 9201997W WO 9309616 A1 WO9309616 A1 WO 9309616A1
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WIPO (PCT)
Prior art keywords
carriers
additional data
frequency
amplitudes
division multiplex
Prior art date
Application number
PCT/GB1992/001997
Other languages
French (fr)
Inventor
John Philip Chambers
Original Assignee
British Broadcasting Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Broadcasting Corporation filed Critical British Broadcasting Corporation
Priority to JP5508251A priority Critical patent/JPH07500712A/en
Priority to DE69227120T priority patent/DE69227120T2/en
Priority to EP92922448A priority patent/EP0611505B1/en
Publication of WO1993009616A1 publication Critical patent/WO1993009616A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
    • H04H20/30—Arrangements for simultaneous broadcast of plural pieces of information by a single channel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/65—Arrangements characterised by transmission systems for broadcast
    • H04H20/67—Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H60/00—Arrangements for broadcast applications with a direct linking to broadcast information or broadcast space-time; Broadcast-related systems
    • H04H60/35—Arrangements for identifying or recognising characteristics with a direct linkage to broadcast information or to broadcast space-time, e.g. for identifying broadcast stations or for identifying users
    • H04H60/49—Arrangements for identifying or recognising characteristics with a direct linkage to broadcast information or to broadcast space-time, e.g. for identifying broadcast stations or for identifying users for identifying locations
    • H04H60/54—Arrangements for identifying or recognising characteristics with a direct linkage to broadcast information or to broadcast space-time, e.g. for identifying broadcast stations or for identifying users for identifying locations where broadcast information is generated
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2649—Demodulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H2201/00—Aspects of broadcast communication
    • H04H2201/10—Aspects of broadcast communication characterised by the type of broadcast system
    • H04H2201/20—Aspects of broadcast communication characterised by the type of broadcast system digital audio broadcasting [DAB]

Definitions

  • This invention relates to a method of coding broadcast transmissions so as to carry additional data, such as for example an identification of the transmitter concerned.
  • the method is applicable to transmission systems using a frequency division multiplex technique- Such a technique is used in the system proposed by Pommier, D. and Ratliff, P.A. in a paper "New Prospects for High Quality Digital Sound Broadcasting to Mobile Portable and Fixed Radio Receivers", IBC 88, IEE Conference Publication No.293, pages 349 to 353.
  • the system involves:
  • the system described has been found to provide excellent reception quality in mobile use even in the presence of substantial multipath propagation.
  • the authors of the above paper propose its use for a single-frequency network of terrestrial digital stereo audio transmitters in the 50-250 MHz range. Because the receiver is able to cope with multipath signals, it does not, in principle, need to know which transmitter the signals have come from. Furthermore any 'holes' in the coverage area may be filled in by providing a local low-power transmitter on the same frequencies as those in the network.
  • the system has reduced potential to interfere with other radio communications services because of its uniform spectral characteristics. All these factors make it an attractive system to use in an already-crowded broadcasting spectrum.
  • the whole point of the single-frequency system described is that the receiver can simultaneously accept signals from more than one transmitter without differentiating between them.
  • the same signal emanates from all transmitters which are carrying the same services.
  • the digital audio broadcasting (DAB) system also known as digital sound broadcasting (DSB), proposed in the above paper has 500 narrowband carriers, and typically there might be between 400 and 1800 carriers. These carriers are used in an orthogonal frequency-division multiplex (OFDM) technique, now generally called the coded orthogonal frequency division multiplex (COFDM) .
  • OFDM orthogonal frequency-division multiplex
  • COFDM coded orthogonal frequency division multiplex
  • a method of transmitting additional data on a broadcast transmission which uses a frequency-division multiplex technique in which the signal is transmitted on a plurality of carriers.
  • the amplitudes of the carriers are relatively varied in accordance with the additional data.
  • FIG. 1 is a block schematic of a DAB transmitter embodying the invention.
  • FIG. 2 is a block schematic of a DAB receiver embodying the invention.
  • the DAB signal is produced by a linear FFT operation it is a simple operation to reduce the amplitude of half the carriers by, say, one sixteenth. As the whole system is designed to adapt to variation of carrier amplitude, this operation does not upset the receivers. On average the effect is equivalent to a loss of, in this example, one thirty-second of the signal amplitude.
  • a standard receiver continues to operate normally in the presence of this systematic and static amplitude modulation.
  • the receiver FFT operation is linear, the evidence is available to allow the amplitude modulation pattern to be inferred by suitable long-term integration and correlation against the known possible patterns.
  • amplitude modulation patterns capable of distinguishing one or more of seven different transmitters received at the same time.
  • the principle can in theory be extended to any number, up to the number of carriers in the DAB system, but the complexity then increases, and the sensitivity decreases.
  • the DAB carriers typically between 400 and 1800 in number, are divided into eight interleaved groups 0-7 by consecutive numbering modulo-8 (i.e. dividing by 8 and looking at the remainder) .
  • each group spans the full bandwidth in a similar way, as opposed to dividing the carriers into eight adjacent groups in the frequency domain.
  • the amplitude of each carrier group from each transmitter A-G is unchanged (0) or attenuated (1) according to the entry in either Table 1 or Table 2 below appended to this description.
  • Each of Tables 1 and 2 provides orthogonality between the amplitude modulation applied to the seven transmitters, allowing the strength of each of the seven patterns in the received signal to be established by correlation in the receiver without interference from the other six. Thus the identity of the contributing transmitters, and their 'average' relative signal strength, can be established.
  • the presently- roposed DAB transmitter waveform comprises a sequence of typically 76 adjacent symbol blocks interrupted every 96ms (or 24ms) by a null period in which the signal is effectively absent.
  • Each symbol block contains some 1536 carriers equi-spaced in frequency and of equal amplitudem differentially modulated from symbol to symbol in one of four phases.
  • the waveform is synthesised by taking the output of a Fast Fourier Transform whose input is the two bits per carrier indicating the required phase of each carrier.
  • Figure 1 indicates how the transmitted signal is assembled in an idealised transmitter 10. Every symbol block period the DAB encoding equipment produces 1536 pairs of bits (in the 96ms case) corresponding to the quadrature phase modulation to be applied to the 1536 equi-spaced carriers. Every symbol period these are loaded into a digital Fast Fourier Transform (FFT) circuit 12 as the input and a similar number of outputs appear.
  • the inputs correspond to the frequency domain, the outputs to the time domain.
  • the inputs are basically two-level, corresponding to a binary bit, the outputs are multi-level (typically eight bits corresponding to 256 equispaced analogue levels).
  • the two sequences of outputs corresponding to the in-phase ("I") and quadrature CQ") parts of the signal, are each passed through digital-to-analogue converters 14, 16 prior to modulation in modulators 18, 20 by the intermediate-frequency carrier which itself is made available in two phases in quadrature as illustrated by 90° phase shift circuit 22.
  • Each operation of the FFT produces one symbol block.
  • the resulting signal, a sequence of symbol blocks, is then up-converted to the r.f. carrier. Note that it is a feature of the DAB system that the centre 'carrier' frequency is, in fact, absent.
  • the received i.f. waveform is split into two by a splitter 32 and demodulated using multipliers 34, 36 with two versions of the local IF oscillator output in phase quadrature, as indicated by 90° phase shift circuits 38, and these analogue signals are converted to a sequence of digitised samples in converters 40, 42.
  • the sequences of samples corresponding to successive symbol blocks are applied in turn to an FFT 44 whose outputs represent the (complex) amplitude of the individual carriers.
  • the absolute and relative amplitudes of the carriers have been corrupted by numerous effects, most importantly the propagation conditions (selective fading, multipath etc.), so these amplitudes are non-ideal.
  • a decision logic circuit 46 is used to produce a logical signal from the (typically eight-bit) carrier amplitude information. Rather than a simple binary threshold decision, this decision logic may produce a (typically) three-bit signal, non-linearly coded to indicate the polarity and the confidence in that particular bit. This information can then be used with appropriate 'weighting' in any 'soft-decision' decoding algorithm which takes advantage of the redundancy in the bits.
  • the inputs to the transmitter FFT 12 are modified by a circuit 26 in a fixed (at least in the short term) pattern, peculiar to each transmitter or group of transmitters, such that the amplitudes of about half the carriers are reduced by a small factor. This is indicated in the figure by the replacement of bits i and q by the levels i' and q' . Such patterns are well spread across the bandwidth and they are mutually orthogonal.
  • the FFT might normally operate with input 01111111 for '0' and 11111111 for '!', using a convention where the first bit is sign, the remaining 7 are magnitude.
  • the input for the reduced carrier might be 01111000 for '0' and 11111000 for '!', a reduction of amplitude from level 127 to level 120.
  • the decision logic circuit 46 may for this purpose include means for comparing the amplitude of the carriers with their mean amplitude to determine whether they are above or below the mean.

Abstract

A broadcast transmission using a frequency-division multiplex technique, such as the so-called DAB or DSB proposed radio system, uses a large number of carriers generated by coding digital information using a fast Fourier transform (12). Additional data is carried by relatively varying the amplitudes of the carriers in a modification circuit (26) by a slight amount in accordance with the additional data. The additional data may comprise transmitter identification. The additional data can be recovered by decision logic (46) in a receiver.

Description

CODING METHOD FOR BROADCAST TRANSMISSIONS
BACKGROUND OF THE INVENTION
This invention relates to a method of coding broadcast transmissions so as to carry additional data, such as for example an identification of the transmitter concerned. The method is applicable to transmission systems using a frequency division multiplex technique- Such a technique is used in the system proposed by Pommier, D. and Ratliff, P.A. in a paper "New Prospects for High Quality Digital Sound Broadcasting to Mobile Portable and Fixed Radio Receivers", IBC 88, IEE Conference Publication No.293, pages 349 to 353. The system involves:
(a) a Fast Fourier Transform (FFT) for both modulation and demodulation processes to overcome frequency selectivity, using many simultaneous narrowband carriers,
(b) convolutional coding in conjunction with a Viterbi maximum-likelihood decoding algorithm to provide a large coding gain,
(c) two-dimensional, frequency and time interleaving to realise the large coding gain in all fixed and mobile receiving conditions, and
(d) an outer blockcode concatenated with the convolutional inner code.
The system described has been found to provide excellent reception quality in mobile use even in the presence of substantial multipath propagation. The authors of the above paper propose its use for a single-frequency network of terrestrial digital stereo audio transmitters in the 50-250 MHz range. Because the receiver is able to cope with multipath signals, it does not, in principle, need to know which transmitter the signals have come from. Furthermore any 'holes' in the coverage area may be filled in by providing a local low-power transmitter on the same frequencies as those in the network. The system has reduced potential to interfere with other radio communications services because of its uniform spectral characteristics. All these factors make it an attractive system to use in an already-crowded broadcasting spectrum.
However, we have appreciated that there are circumstances when it would be desirable to be able to identify individual transmitters in such a single-frequency network. For the broadcaster, this would be of assistance for monitoring and measurement purposes. In a sophisticated receiver, this information could be of assistance for example in navigation or in selecting services appropriate to a particular geographical area.
However, the whole point of the single-frequency system described is that the receiver can simultaneously accept signals from more than one transmitter without differentiating between them. The same signal emanates from all transmitters which are carrying the same services.
The digital audio broadcasting (DAB) system, also known as digital sound broadcasting (DSB), proposed in the above paper has 500 narrowband carriers, and typically there might be between 400 and 1800 carriers. These carriers are used in an orthogonal frequency-division multiplex (OFDM) technique, now generally called the coded orthogonal frequency division multiplex (COFDM) .
SUMMARY OF THE INVENTION
According to the present invention a method of transmitting additional data on a broadcast transmission which uses a frequency-division multiplex technique is provided, in which the signal is transmitted on a plurality of carriers. The amplitudes of the carriers are relatively varied in accordance with the additional data. BRIEF DESCRIPTION OF THE DRAWINGS
The system will be described by way of example with reference to the DAB system proposed in the above paper and with reference to the drawings, in which:
Figure 1 is a block schematic of a DAB transmitter embodying the invention; and
Figure 2 is a block schematic of a DAB receiver embodying the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As the DAB signal is produced by a linear FFT operation it is a simple operation to reduce the amplitude of half the carriers by, say, one sixteenth. As the whole system is designed to adapt to variation of carrier amplitude, this operation does not upset the receivers. On average the effect is equivalent to a loss of, in this example, one thirty-second of the signal amplitude.
A standard receiver continues to operate normally in the presence of this systematic and static amplitude modulation. However, because the receiver FFT operation is linear, the evidence is available to allow the amplitude modulation pattern to be inferred by suitable long-term integration and correlation against the known possible patterns.
A particular example of amplitude modulation patterns will now be given, capable of distinguishing one or more of seven different transmitters received at the same time. The principle can in theory be extended to any number, up to the number of carriers in the DAB system, but the complexity then increases, and the sensitivity decreases.
The DAB carriers, typically between 400 and 1800 in number, are divided into eight interleaved groups 0-7 by consecutive numbering modulo-8 (i.e. dividing by 8 and looking at the remainder) . Thus each group spans the full bandwidth in a similar way, as opposed to dividing the carriers into eight adjacent groups in the frequency domain. The amplitude of each carrier group from each transmitter A-G is unchanged (0) or attenuated (1) according to the entry in either Table 1 or Table 2 below appended to this description.
Each of Tables 1 and 2 provides orthogonality between the amplitude modulation applied to the seven transmitters, allowing the strength of each of the seven patterns in the received signal to be established by correlation in the receiver without interference from the other six. Thus the identity of the contributing transmitters, and their 'average' relative signal strength, can be established.
For further information concerning the structure and operation of the proposed DAB system reference should be made to the Proceedings of the First International Symposium on Digital Audio Broadcasting, Montreur, 8-9 June 1992, organised by the European Broadcasting Union and others. A preferred example of a DAB transmitter/receiver system embodying the invention will now be described with reference to the drawings.
The presently- roposed DAB transmitter waveform comprises a sequence of typically 76 adjacent symbol blocks interrupted every 96ms (or 24ms) by a null period in which the signal is effectively absent. Each symbol block contains some 1536 carriers equi-spaced in frequency and of equal amplitudem differentially modulated from symbol to symbol in one of four phases. In practice, the waveform is synthesised by taking the output of a Fast Fourier Transform whose input is the two bits per carrier indicating the required phase of each carrier.
Figure 1 indicates how the transmitted signal is assembled in an idealised transmitter 10. Every symbol block period the DAB encoding equipment produces 1536 pairs of bits (in the 96ms case) corresponding to the quadrature phase modulation to be applied to the 1536 equi-spaced carriers. Every symbol period these are loaded into a digital Fast Fourier Transform (FFT) circuit 12 as the input and a similar number of outputs appear. The inputs correspond to the frequency domain, the outputs to the time domain. Although the inputs are basically two-level, corresponding to a binary bit, the outputs are multi-level (typically eight bits corresponding to 256 equispaced analogue levels). The two sequences of outputs, corresponding to the in-phase ("I") and quadrature CQ") parts of the signal, are each passed through digital-to-analogue converters 14, 16 prior to modulation in modulators 18, 20 by the intermediate-frequency carrier which itself is made available in two phases in quadrature as illustrated by 90° phase shift circuit 22. Each operation of the FFT produces one symbol block. The resulting signal, a sequence of symbol blocks, is then up-converted to the r.f. carrier. Note that it is a feature of the DAB system that the centre 'carrier' frequency is, in fact, absent.
In a receiver as shown in Figure 2 the received i.f. waveform is split into two by a splitter 32 and demodulated using multipliers 34, 36 with two versions of the local IF oscillator output in phase quadrature, as indicated by 90° phase shift circuits 38, and these analogue signals are converted to a sequence of digitised samples in converters 40, 42. The sequences of samples corresponding to successive symbol blocks are applied in turn to an FFT 44 whose outputs represent the (complex) amplitude of the individual carriers. In practice, the absolute and relative amplitudes of the carriers have been corrupted by numerous effects, most importantly the propagation conditions (selective fading, multipath etc.), so these amplitudes are non-ideal. A decision logic circuit 46 is used to produce a logical signal from the (typically eight-bit) carrier amplitude information. Rather than a simple binary threshold decision, this decision logic may produce a (typically) three-bit signal, non-linearly coded to indicate the polarity and the confidence in that particular bit. This information can then be used with appropriate 'weighting' in any 'soft-decision' decoding algorithm which takes advantage of the redundancy in the bits.
In the invention described the inputs to the transmitter FFT 12 are modified by a circuit 26 in a fixed (at least in the short term) pattern, peculiar to each transmitter or group of transmitters, such that the amplitudes of about half the carriers are reduced by a small factor. This is indicated in the figure by the replacement of bits i and q by the levels i' and q' . Such patterns are well spread across the bandwidth and they are mutually orthogonal. Typically the FFT might normally operate with input 01111111 for '0' and 11111111 for '!', using a convention where the first bit is sign, the remaining 7 are magnitude. In such a case the input for the reduced carrier might be 01111000 for '0' and 11111000 for '!', a reduction of amplitude from level 127 to level 120.
Such a systematic modification to the carriers will not affect the normal operation of a receiver but receivers can be equipped with additional logic in the decision logic circuit 46 to 'integrate out' by correlation both the pattern of each transmitter contributing to the signal and its relative contribution to the total signal strength' . The decision logic circuit 46 may for this purpose include means for comparing the amplitude of the carriers with their mean amplitude to determine whether they are above or below the mean.
There is a trade-off between the number of different orthogonal patterns used, the variation of amplitude, and the time taken before a reliable indication can be received. It is expected that a response within a few seconds would be practicable with a relatively modest amplitude variation. Of course, occasional changes to the transmitter identification patterns over a time scale longer than this response time could be made as a form of low bit-rate signalling.
Note that a reduction in about half of the carrier amplitudes has been described, on the assumption that the transmitter FFT is normally loaded with 'full house' binary numbers. If, for design reasons, lower numbers are used, the same effect could be achieved by increasing some amplitudes, or the mean amplitude could be preserved by increasing some and decreasing others with respect to the normal.
TABLE 1
Figure imgf000009_0001
TABLE 2
0 1
Figure imgf000009_0002

Claims

1. A method of transmitting additional data on a broadcast transmission which was a frequency-division multiplex technique, in which the signal is transmitted on a plurality of carriers, the amplitudes of the carriers being relatively varied in accordance with the additional data.
2. A method according to claim 1, in which the additional data includes data identifying the transmitter.
3. A method according to claim 1, in which the amplitudes of selected ones of the carriers are reduced by a small amount.
4. A method according to claim 1, in which the carriers are grouped and the amplitudes of groups of carriers varied to encode the additional data.
5. A method according to claim 4-, in which the groups are interleaved in the spectrum.
6. A transmitter for transmitting additional data on a broadcast transmission which uses a frequency-division multiplex technique, comprising means for generating a broadcast transmission signal using a frequency-division multiplex technique having a plurality of carriers, and means for relatively varying the amplitudes of the carriers in accordance with additional data.
7. A transmitter network comprising a plurality of transmitters, each transmitter comprising means for generating a broadcast transmission signal using a frequency-division multiplex technique having a plurality of carriers, and means for relatively varying the amplitudes of the carriers in accordance with additional data and in which the coding algorithms used in the different transmitters provide orthogonality between the amplitude modulation applied to the transmitters.
8. A receiver for receiving a broadcast transmission transmitted using a frequency-division multiplex technique and carrying additional information, the receiver comprising means for receiving and demodulating the plurality of carriers carrying the signal in the frequency-division multiplex technique, and means for determining relative variation between the amplitudes of the carriers to extract the additional data therefrom.
PCT/GB1992/001997 1991-11-04 1992-11-02 Coding method for broadcast transmissions WO1993009616A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP5508251A JPH07500712A (en) 1991-11-04 1992-11-02 Encoding method for broadcasting transmission signals
DE69227120T DE69227120T2 (en) 1991-11-04 1992-11-02 ENCODING METHOD FOR FDM BROADCASTING, TRANSMITTERS AND RECEIVERS FOR IMPLEMENTING THE METHOD
EP92922448A EP0611505B1 (en) 1991-11-04 1992-11-02 Coding method for fdm broadcast transmissions, transmitter and receiver for carrying out the method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9123376.7 1991-11-04
GB919123376A GB9123376D0 (en) 1991-11-04 1991-11-04 Coding method for broadcast transmissions

Publications (1)

Publication Number Publication Date
WO1993009616A1 true WO1993009616A1 (en) 1993-05-13

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Country Status (7)

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EP (1) EP0611505B1 (en)
JP (1) JPH07500712A (en)
CN (1) CN1035590C (en)
AU (1) AU2798392A (en)
DE (1) DE69227120T2 (en)
GB (2) GB9123376D0 (en)
WO (1) WO1993009616A1 (en)

Cited By (2)

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WO1995024780A1 (en) * 1994-03-11 1995-09-14 British Broadcasting Corporation Digital broadcast systems for local transmissions
EP0692889A1 (en) * 1994-07-14 1996-01-17 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH & Co. KG Method, transmitter and receiver for transmission and selection of local broadcast programmes in a common wave network

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DE4341211C1 (en) * 1993-12-03 1995-04-20 Grundig Emv Method and circuit arrangement for inserting data into a transmission signal
US5825826A (en) * 1996-09-30 1998-10-20 Motorola, Inc. Method and apparatus for frequency domain ripple compensation for a communications transmitter
DE19715022A1 (en) * 1997-04-11 1998-10-15 Deutsche Telekom Ag System for the transmission of high-rate value-added services in terrestrial broadcasting
JP2000115116A (en) 1998-10-07 2000-04-21 Nippon Columbia Co Ltd Orthogonal frequency division multiplex signal generator, orthogonal frequency division multiplex signal generation method and communication equipment
EP1087585B1 (en) 1999-09-17 2013-08-21 Alcatel-Lucent Identification of a terrestrial repeater using inactive subcarriers of a multicarrier signal
US6347216B1 (en) * 1999-11-04 2002-02-12 Xm Satellite Radio Inc. Method and system for providing geographic specific services in a satellite communications network
US7564907B2 (en) * 2005-06-15 2009-07-21 Delphi Technologies, Inc. Technique for providing secondary data in a single-frequency network
ITUB20154079A1 (en) * 2015-10-02 2017-04-02 Inst Fur Rundfunktechnik Gmbh IDENTIFICATION OF THE TRANSMITTER

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995024780A1 (en) * 1994-03-11 1995-09-14 British Broadcasting Corporation Digital broadcast systems for local transmissions
EP0692889A1 (en) * 1994-07-14 1996-01-17 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH & Co. KG Method, transmitter and receiver for transmission and selection of local broadcast programmes in a common wave network
WO1996002988A1 (en) * 1994-07-14 1996-02-01 Grundig E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig Gmbh & Co. Kg Process, sender and receiver for transmitting and selecting local radio programs in a common-wave broadcasting network
AU694976B2 (en) * 1994-07-14 1998-08-06 Delphi Technologies, Inc. Process sender and receiver for transmitting and selecting local radio program s in a common wave broadcasting network

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GB2261142A (en) 1993-05-05
EP0611505B1 (en) 1998-09-23
DE69227120D1 (en) 1998-10-29
CN1035590C (en) 1997-08-06
GB9222940D0 (en) 1992-12-16
CN1072548A (en) 1993-05-26
GB9123376D0 (en) 1991-12-18
DE69227120T2 (en) 1999-02-18
AU2798392A (en) 1993-06-07
JPH07500712A (en) 1995-01-19
EP0611505A1 (en) 1994-08-24

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